AD/DHA-3/21 - Corrosion of Wing and Centre Section Spar Booms - Inspection (Cth)

COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES

DHA-3 (Drover) Series Aeroplanes

AD/DHA-3/21 Corrosion of Wing and Centre Section Spar Booms - Inspection

9/71

Applicability: All models.

Requirement: 1.1 Inspect all accessible areas of the centre section spar upper and lower booms and wing spar booms for the presence of intercrystalline corrosion as follows:

Note: Intercrystalline corrosion may be recognised by the presence of blisters on the surface of the material or flaking parallel to the grain flow.

1.2 For the purpose of the inspection, temporarily remove the following items from the aeroplane:

(a) Seats and cabin equipment affecting access to centre section spar web cut- outs.

(b) Wing fillets.

(c) Tank doors.

(d) Wing leading edge between fuselage and engine nacelles.

(e) Protective coating from the accessible areas of the centre section upper and lower spare booms.

Note: Restore protective coating when the inspection is completed.

1.3 Inspect the following areas using a mirror where necessary:

(a) All visible surfaces of the centre section upper and lower booms including the interior surfaces.

(b) Vertical and horizontal surfaces of the upper and lower spar booms in the tank bays.

(c) All sections of the wing spar booms visible through existing inspection holes and lighting holes in the auxiliary spars.

(d) If corrosion is found on the exposed portions of the upper or lower spar booms and the aileron pulley bracks (P/N FS3-5109A and FS3-5113A) are to be removed and the mating surfaces of the brackets and spars are to be inspected for corrosion.